Simplify by using Gnulib sigdescr_np module

Inspired by a straightforward patch by Bruno Haible.
* admin/merge-gnulib (GNULIB_MODULES): Add sigdescr_np.
* configure.ac: Do not check for sys_siglist or __sys_siglist.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lib/sigdescr_np.c, m4/sigdescr_np.m4: New files, copied from Gnulib.
* src/sysdep.c (sys_siglist, sys_siglist_entries): Remove.
(init_signals): Do not initialize sys_siglist.
(safe_strsignal): Use sigdescr_np instead of sys_siglist.

2 files changed, 388 insertions, 0 deletions

diff --git a/lib/gnulib.mk.in b/lib/gnulib.mk.in
index 86eb14383c1..f564d501222 100644
--- a/lib/gnulib.mk.in
+++ b/lib/gnulib.mk.in
@@ -136,6 +136,7 @@
 #  readlinkat \
 #  regex \
 #  sig2str \
+#  sigdescr_np \
 #  socklen \
 #  stat-time \
 #  std-gnu11 \
@@ -2314,6 +2315,17 @@ EXTRA_libgnu_a_SOURCES += sig2str.c
 endif
 ## end   gnulib module sig2str
 
+## begin gnulib module sigdescr_np
+ifeq (,$(OMIT_GNULIB_MODULE_sigdescr_np))
+
+
+EXTRA_DIST += sigdescr_np.c
+
+EXTRA_libgnu_a_SOURCES += sigdescr_np.c
+
+endif
+## end   gnulib module sigdescr_np
+
 ## begin gnulib module signal-h
 ifeq (,$(OMIT_GNULIB_MODULE_signal-h))
 
diff --git a/lib/sigdescr_np.c b/lib/sigdescr_np.c
new file mode 100644
index 00000000000..fc9cd3c2369
--- /dev/null
+++ b/lib/sigdescr_np.c
@@ -0,0 +1,376 @@
+/* English descriptions of signals.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2020.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <string.h>
+
+#include <signal.h>
+
+const char *
+sigdescr_np (int sig)
+{
+  /* Note: Some platforms (glibc, FreeBSD, NetBSD, OpenBSD, AIX, IRIX, Haiku,
+     Android) have an array 'sys_siglist'.  (On AIX, you need to declare it
+     yourself, and it has fewer than NSIG elements.)  Its contents varies
+     depending on the OS.
+     On other OSes, you can invoke strsignal (sig) in the C locale.
+     In the code below, we show the differences.
+     You can see how cryptic some of these strings are.  We try to pick more
+     understandable wordings.  */
+
+  switch (sig)
+    {
+    /* Signals specified by ISO C.  */
+    case SIGABRT:
+      /* glibc: "Aborted".  *BSD: "Abort trap".  Solaris: "Abort".  */
+      return "Aborted";
+    case SIGFPE:
+      /* glibc, *BSD: "Floating point exception".  Solaris: "Arithmetic exception".
+         The latter is more correct, because of integer division by 0 or -1.  */
+      return "Arithmetic exception";
+    case SIGILL:
+      return "Illegal instruction";
+    case SIGINT:
+      return "Interrupt";
+    case SIGSEGV:
+      return "Segmentation fault";
+    case SIGTERM:
+      return "Terminated";
+
+    /* Signals specified by POSIX.
+       <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/signal.h.html>  */
+    #if defined SIGALRM
+    case SIGALRM:
+      return "Alarm clock";
+    #endif
+    #if defined SIGBUS
+    case SIGBUS:
+      return "Bus error";
+    #endif
+    #if defined SIGCHLD
+    case SIGCHLD:
+      /* glibc, *BSD: "Child exited".  Solaris: "Child status changed".  */
+      return "Child stopped or exited";
+    #endif
+    #if defined SIGCONT
+    case SIGCONT:
+      return "Continued";
+    #endif
+    #if defined SIGHUP
+    case SIGHUP:
+      return "Hangup";
+    #endif
+    #if defined SIGKILL
+    case SIGKILL:
+      return "Killed";
+    #endif
+    #if defined SIGPIPE
+    case SIGPIPE:
+      return "Broken pipe";
+    #endif
+    #if defined SIGQUIT
+    case SIGQUIT:
+      return "Quit";
+    #endif
+    #if defined SIGSTOP
+    case SIGSTOP:
+      /* glibc, Solaris: "Stopped (signal)".  *BSD: "Suspended (signal)".  */
+      return "Stopped (signal)";
+    #endif
+    #if defined SIGTSTP
+    case SIGTSTP:
+      /* glibc: "Stopped".  *BSD: "Suspended".  Solaris: "Stopped (user)".  */
+      return "Stopped";
+    #endif
+    #if defined SIGTTIN
+    case SIGTTIN:
+      return "Stopped (tty input)";
+    #endif
+    #if defined SIGTTOU
+    case SIGTTOU:
+      return "Stopped (tty output)";
+    #endif
+    #if defined SIGUSR1
+    case SIGUSR1:
+      /* glibc, *BSD: "User defined signal 1".  Solaris: "User signal 1".  */
+      return "User defined signal 1";
+    #endif
+    #if defined SIGUSR2
+    case SIGUSR2:
+      /* glibc, *BSD: "User defined signal 2".  Solaris: "User signal 2".  */
+      return "User defined signal 2";
+    #endif
+    #if defined SIGPOLL
+    case SIGPOLL:
+      /* glibc: "I/O possible".  Solaris: "Pollable event".  */
+      return "I/O possible";
+    #endif
+    #if defined SIGPROF
+    case SIGPROF:
+      return "Profiling timer expired";
+    #endif
+    #if defined SIGSYS
+    case SIGSYS:
+      return "Bad system call";
+    #endif
+    #if defined SIGTRAP
+    case SIGTRAP:
+      /* glibc, Solaris: "Trace/breakpoint trap".  *BSD: "Trace/BPT trap".  */
+      return "Trace/breakpoint trap";
+    #endif
+    #if defined SIGURG
+    case SIGURG:
+      /* glibc, *BSD: "Urgent I/O condition".  Solaris: "Urgent socket condition".  */
+      return "Urgent I/O condition";
+    #endif
+    #if defined SIGVTALRM
+    case SIGVTALRM:
+      return "Virtual timer expired";
+    #endif
+    #if defined SIGXCPU
+    case SIGXCPU:
+      /* glibc, *BSD: "CPU time limit exceeded".  Solaris: "Cpu limit exceeded".  */
+      return "CPU time limit exceeded";
+    #endif
+    #if defined SIGXFSZ
+    case SIGXFSZ:
+      return "File size limit exceeded";
+    #endif
+
+    /* Other signals on other systems.  */
+    /* native Windows */
+    #if defined SIGBREAK
+    case SIGBREAK:
+      return "Ctrl-Break";
+    #endif
+    /* IRIX */
+    #if defined SIGCKPT
+    case SIGCKPT:
+      return "Checkpoint"; /* See man 1 cpr, man 3C atcheckpoint */
+    #endif
+    /* Linux, IRIX, Cygwin */
+    #if defined SIGCLD && SIGCLD != SIGCHLD
+    case SIGCLD:
+      return "Child stopped or exited";
+    #endif
+    /* AIX */
+    #if defined SIGCPUFAIL
+    case SIGCPUFAIL:
+      /* AIX: "CPU failure predicted".  */
+      return "CPU going down"; /* See man bindprocessor */
+    #endif
+    /* AIX */
+    #if defined SIGDANGER
+    case SIGDANGER:
+      /* AIX: "Paging space low".  */
+      return "Swap space nearly exhausted";
+    #endif
+    /* Mac OS X, FreeBSD, NetBSD, OpenBSD, Minix, AIX, IRIX, Cygwin, mingw */
+    #if defined SIGEMT
+    case SIGEMT:
+      /* glibc/Hurd, *BSD: "EMT trap".  Solaris: "Emulation trap".  */
+      return "Instruction emulation needed";
+    #endif
+    /* Mac OS X, FreeBSD, NetBSD, OpenBSD, Minix */
+    #if defined SIGINFO
+    case SIGINFO:
+      return "Information request";
+    #endif
+    /* Linux, Mac OS X, FreeBSD, NetBSD, OpenBSD, Minix, AIX, IRIX, Cygwin */
+    #if defined SIGIO && SIGIO != SIGPOLL
+    case SIGIO:
+      return "I/O possible";
+    #endif
+    /* Linux, IRIX, Cygwin, mingw */
+    #if defined SIGIOT && SIGIOT != SIGABRT
+    case SIGIOT:
+      return "IOT instruction"; /* a PDP-11 instruction */
+    #endif
+    /* AIX */
+    #if defined SIGKAP
+    case SIGKAP:
+      /* Process must issue a KSKAPACK ioctl, or will be killed in 30 seconds.  */
+      /* AIX: "Monitor mode granted".  */
+      return "Keep Alive Poll";
+    #endif
+    /* Haiku */
+    #if defined SIGKILLTHR
+    case SIGKILLTHR:
+      return "Kill thread";
+    #endif
+    /* Minix */
+    #if defined SIGKMEM
+    case SIGKMEM:
+      return "Kernel memory request";
+    #endif
+    /* Minix */
+    #if defined SIGKMESS
+    case SIGKMESS:
+      return "Kernel message";
+    #endif
+    /* Minix */
+    #if defined SIGKSIG
+    case SIGKSIG:
+      return "Kernel signal";
+    #endif
+    /* Minix */
+    #if defined SIGKSIGSM
+    case SIGKSIGSM:
+      return "Kernel signal for signal manager";
+    #endif
+    /* FreeBSD */
+    #if defined SIGLIBRT
+    case SIGLIBRT:
+      return "Real-time library interrupt";
+    #endif
+    /* Cygwin */
+    #if defined SIGLOST && SIGLOST != SIGABRT && SIGLOST != SIGPWR
+    case SIGLOST:
+      /* Solaris: "Resource lost".  */
+      return "File lock lost";
+    #endif
+    /* AIX */
+    #if defined SIGMIGRATE
+    case SIGMIGRATE:
+      return "Process migration";
+    #endif
+    /* AIX */
+    #if defined SIGMSG
+    case SIGMSG:
+      /* AIX: "Input device data".  */
+      return "Message in the ring";
+    #endif
+    /* ACM */
+    #if defined SIGPLAN
+    case SIGPLAN:
+      return "Programming language anomaly";
+    #endif
+    /* AIX */
+    #if defined SIGPRE
+    case SIGPRE:
+      return "Programmed exception";
+    #endif
+    /* IRIX */
+    #if defined SIGPTINTR
+    case SIGPTINTR:
+      return "Pthread interrupt";
+    #endif
+    /* IRIX */
+    #if defined SIGPTRESCHED
+    case SIGPTRESCHED:
+      return "Pthread rescheduling";
+    #endif
+    /* Linux, NetBSD, Minix, AIX, IRIX, Cygwin */
+    #if defined SIGPWR
+    case SIGPWR:
+      /* glibc: "Power failure".  NetBSD: "Power fail/restart".  */
+      return "Power failure";
+    #endif
+    /* AIX */
+    #if defined SIGRECONFIG
+    case SIGRECONFIG:
+      return "Dynamic logical partitioning changed";
+    #endif
+    /* AIX */
+    #if defined SIGRECOVERY
+    case SIGRECOVERY:
+      return "Kernel recovery";
+    #endif
+    /* IRIX */
+    #if defined SIGRESTART
+    case SIGRESTART:
+      return "Checkpoint restart"; /* See man 1 cpr, man 3C atrestart */
+    #endif
+    /* AIX */
+    #if defined SIGRETRACT
+    case SIGRETRACT:
+      /* AIX: "Monitor mode retracted".  */
+      return "Retracting Keep Alive Poll";
+    #endif
+    /* AIX */
+    #if defined SIGSAK
+    case SIGSAK:
+      /* AIX: "Secure attention".  */
+      return "Secure Attention Key";
+    #endif
+    /* ACM */
+    #if defined SIGSAM
+    case SIGSAM:
+      return "Symbolic computation failed";
+    #endif
+    /* Minix */
+    #if defined SIGSNDELAY
+    case SIGSNDELAY:
+      return "Done sending message";
+    #endif
+    /* AIX */
+    #if defined SIGSOUND
+    case SIGSOUND:
+      /* AIX: "Sound completed".  */
+      return "Sound configuration changed";
+    #endif
+    /* Linux */
+    #if defined SIGSTKFLT
+    case SIGSTKFLT:
+      return "Stack fault";
+    #endif
+    /* AIX */
+    #if defined SIGSYSERROR
+    case SIGSYSERROR:
+      return "Kernel error";
+    #endif
+    /* AIX */
+    #if defined SIGTALRM
+    case SIGTALRM:
+      return "Thread alarm clock";
+    #endif
+    /* FreeBSD, OpenBSD */
+    #if defined SIGTHR
+    case SIGTHR:
+      /* OpenBSD: "Thread AST".  */
+      return "Thread library interrupt";
+    #endif
+    /* IRIX */
+    #if defined SIGUME
+    case SIGUME:
+      return "Uncorrectable memory error";
+    #endif
+    /* AIX */
+    #if defined SIGVIRT
+    case SIGVIRT:
+      return "Virtual time alarm clock";
+    #endif
+    /* AIX */
+    #if defined SIGWAITING
+    case SIGWAITING:
+      /* AIX: "No runnable lwp".  */
+      return "Thread waiting";
+    #endif
+    /* Linux, Mac OS X, FreeBSD, NetBSD, OpenBSD, Minix, AIX, IRIX, Cygwin, Haiku */
+    #if defined SIGWINCH
+    case SIGWINCH:
+      /* glibc: "Window changed".  *BSD: "Window size changed" or "Window size changes".  */
+      return "Window size changed";
+    #endif
+
+    default:
+      return NULL;
+    }
+}